Chloride salts, and particularly sodium chloride, are commonly used deicers for many highway winter maintenance applications due to the low cost of the salts. However, the chloride ion is very corrosive to a variety of metals, especially to mild steel. Thus, in areas that are particularly sensitive to corrosion, it is often desirable to use a non-chloride deicer. Examples of commonly used non-chloride deicers include carboxylate salts such as sodium acetate, sodium formate, calcium magnesium acetate, and potassium acetate. Because these chemicals contain no chloride, they are far less corrosive to the variety of metals and alloys in aircrafts and are therefore the preferred deicers for airport runways, where chlorides cannot be tolerated. Liquid potassium acetate in particular is a very popular runway deicer for airport runways. Potassium acetate has been shown to have acceptably low corrosion towards the metals specified by the SAE Standard AMS 1435A for liquid runway deicers, including aluminum alloys, anodized aluminum alloys, magnesium alloys, titanium alloys, mild steel, and low embrittling cadmium plate.
While potassium acetate is adequately non-corrosive to the metals specified in AMS 1435A, it and the other carboxylate salt deicers are extremely corrosive towards zinc and galvanized steel. This often renders the use of potassium acetate in many areas, including airport runways, undesirable. Airports often have large investments in galvanized steel structures, such as runway lights, for runways. In order to avoid galvanized steel corrosion, airports often use propylene glycol rather than potassium acetate. Propylene glycol is not as corrosive towards galvanized steel but has certain disadvantages compared to carboxylate salt deicers. For example, propylene glycol is less environmentally friendly, having a much higher biological oxygen demand than potassium acetate.
There is therefore a need for an improved salt deicer with reduced corrosiveness towards zinc and galvanized steel than the conventional carboxylate salt deicers.